SU (said 'S-U', not 'sue')stands for socially unacceptable. It is mainly used as an interjection or adjective to describe things that are socially unacceptable, weird, bizarre, or simply inappropriate in a give situation.

SU (said 'S-U', not 'sue')stands for socially unacceptable. It is mainly used as an interjection or adjective to describe things that are socially unacceptable, werid, bizarre, or simply inappropriate in a give situation.

S.U. (said 'S-U' not 'sue') stands for socially unacceptable. It can be used in many ways but is often used as an exclamation. It describes situations which are akward, tense, or actions which are inappropriate in a given situation, or simply unacceptable according to social norms.

Did you just ask that complete stranger if you have something in your teeth? SU.